Multi-chip package

ABSTRACT

Provided are multi-chip packages. A multi-chip package includes a first memory chip and a second memory chip on a printed circuit board; a memory controller electrically connected to the first memory chip and the second memory chip via a first bonding wire and a second bonding wire; and a strength control module configured to control a drive strength of each of a first output driver of the first memory chip and a second output driver of the second memory chip, wherein the memory controller includes an interface circuit configured to receive each of first test data and second test data from the first output driver and the second output driver in which the drive strength is set by the strength control module, and output detection data for detecting whether the first bonding wire and the bonding wire are short-circuited based on the first and second test data.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Korean Patent Application No.10-2019-0003644 filed on Jan. 11, 2019 in the Korean IntellectualProperty Office, and all the benefits accruing therefrom under 35 U.S.C.119, the contents of which in its entirety are herein incorporated byreference.

BACKGROUND 1. Technical Field

The present disclosure relates to a multi-chip package.

2. Description of the Related Art

A plurality of semiconductor chips are mounted inside a multi-chippackage. The plurality of semiconductor chips mounted inside themulti-chip package is electrically connected to each other via bondingwires inside the multi-chip package. Here, when the multi-chip packagecorresponds to a memory system such as an embedded multimedia card(eMMC) system and a universal flash storage (UFS) system, the pluralityof semiconductor chips may include a plurality of (nonvolatile) memorychips that stores data, and a memory controller that controls andaccesses the plurality of memory chips.

The bonding wires between the memory controller and the plurality ofmemory chips are not directly connected to an external terminal of themulti-chip package. Therefore, in the case of a defect such as a shortof two bonding wires or a defect in which an open channel is formedbetween the memory controller and the memory chip occurs, it isdifficult to detect the defect only with the signal applied to theexternal terminal.

SUMMARY

Aspects of the present disclosure provide a multi-chip package foraccurately detecting defects such as short-circuit and open which mayoccur inside the multi-chip package.

However, aspects of the present disclosure are not restricted to the oneset forth herein. The above and other aspects of the present disclosurewill become more apparent to one of ordinary skill in the art to whichthe present disclosure pertains by referencing the detailed descriptionof the present disclosure given below.

According to an aspect of the present disclosure, there is provided amulti-chip package including: a first memory chip and a second memorychip on a printed circuit board; a memory controller electricallyconnected to the first memory chip and the second memory chip via afirst bonding wire and a second bonding wire; and a strength controlmodule configured to control a drive strength of each of a first outputdriver of the first memory chip and a second output driver of the secondmemory chip, wherein the memory controller includes an interface circuitconfigured to receive each of first test data and second test data fromthe first output driver and the second output driver in which the drivestrength is set by the strength control module, and output detectiondata for detecting whether the first bonding wire and the bonding wireare short-circuited based on the first and second test data.

According to another aspect of the present disclosure, there is provideda multi-chip package including: a memory chip on a printed circuitboard; a memory controller electrically connected to the memory chipthrough a bonding wire and including an interface circuit for drivingthe memory chip; and a strength control module configured torespectively control drive strengths of output drivers of the memorychip and the interface circuit, wherein the interface circuit isconfigured to output, using the output drivers of the memory chip andthe interface circuit, detection data for detecting whether an openchannel between the memory chip and the interface circuit exists.

According to still another aspect of the present disclosure, there isprovided a multi-chip package including: a memory chip on a printedcircuit board; and a memory controller electrically connected to thememory chip through a bonding wire and includes an interface circuitconfigured to drive the memory chip, wherein the interface circuitincludes a first drive transistor configured to provide a power supplyvoltage to the memory chip, and a second drive transistor configured toprovide a ground voltage to the memory chip, and the interface circuitconfigured to detect, using the first drive transistor and the seconddrive transistor, whether a channel between the memory chip and thememory controller is opened.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects and features of the present disclosure willbecome more apparent by describing in detail example embodiments thereofwith reference to the attached drawings, in which:

FIG. 1 is a cross-sectional view illustrating a multi-chip packageaccording to an example embodiment of the present disclosure;

FIG. 2 is a block diagram illustrating an operation in a normal mode ofthe multi-chip package of FIG. 1;

FIG. 3 is a diagram illustrating an example embodiment of an interfacecircuit 135 of the multi-chip package of FIG. 2;

FIG. 4 is a block diagram illustrating an operation example in a testmode of the multi-chip package of FIG. 1;

FIG. 5 is a view illustrating an operation example of the interfacecircuit 135 of the multi-chip package of FIG. 4;

FIG. 6 is a block diagram illustrating an operation example in the testmode of the multi-chip package of FIG. 1;

FIG. 7 is a diagram illustrating an operation example of the interfacecircuit 135 of the multi-chip package of FIG. 6;

FIG. 8 is a table illustrating the operation of the multi-chip packageof FIG. 1;

FIG. 9 is a cross-sectional view illustrating a multi-chip packageaccording to an example embodiment of the present disclosure;

FIG. 10 is a block diagram illustrating the multi-chip package of FIG.9;

FIG. 11 is a block diagram illustrating an operation example in the testmode of the multi-chip package of FIG. 9;

FIG. 12 is a block diagram illustrating a multi-chip package accordingto an example embodiment of the present disclosure;

FIG. 13 is a block diagram illustrating an operation example in the testmode of the multi-chip package of FIG. 12;

FIG. 14 is a block diagram illustrating a multi-chip package accordingto an example embodiment of the present disclosure; and

FIG. 15 is a block diagram illustrating an operation example in the testmode of the multi-chip package of FIG. 14.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, example embodiments of the present disclosure will bedescribed with reference to the accompanying drawings. However, thosehaving ordinary skill in the technical field to which the presentdisclosure belongs will appreciate that the present disclosure may beimplemented in other specific forms without changing the technical ideasor essential features thereof. It is therefore to be understood that theexample embodiments described below are illustrative rather thanrestrictive in all respects.

FIG. 1 is a cross-sectional view illustrating a multi-chip packageaccording to an example embodiment of the present disclosure.

Referring to FIG. 1, the multi-chip package 1 includes a package 100 andan external terminal 110. Further, the package 100 includes asemiconductor chip 130 and a plurality of semiconductor chips 141 to 148mounted on the printed circuit board 120.

It will be understood that, as described herein, an element that is “on”another element may be “above” or “below” the other element.Additionally, it will be understood that, as described herein, anelement that is “on” another element may be directly on the otherelement, such that the elements are in direct contact with each other,or may be indirectly on the other elements, such that the elements areisolated from direct contact with each other by one or more interposingstructures and/or spaces.

Here, the multi-chip package 1 may be a memory system that provides alarge-capacity and high-speed memory device. For example, the multi-chippackage 1 may be an embedded multi media card (eMMC system) or auniversal flash storage (UFS) system which includes a NAND typeflash-based nonvolatile memory device, that is, a plurality ofsemiconductor chips 141 to 148, and includes a memory controller forcontrolling the nonvolatile memory device, that is, a semiconductor chip130.

In this specification, for the sake of convenience of explanation,assuming that the multi-chip package 1 is implemented as such a memorysystem, the semiconductor chip 130 will be described as a memorycontroller 130, and the plurality of semiconductor chips 141 to 148 willbe described as a plurality of memory chips 141 to 148. However, thescope of the present disclosure is not limited thereto, and thesemiconductor chips 130 and the plurality of semiconductor chips 141 to148 may be implemented as a chip including an arbitrary semiconductorcircuit.

On the other hand, in some example embodiments of the presentdisclosure, the multi-chip package 1 may be implemented as packages suchas a PoP (Package On Package), a BGA (Ball Grid Arrays), a CSP (ChipScale Package), a PLCC (Plastic Leaded Chip Carrier), a PDIP (PlasticDual In-line Package), Die in Waffle Pack, Die in Wafer Form, a COB(Chip On Board), a CERDIP (CERamic Dual In-line Package), a MQFP (MetalQuad Flat Package), a TQFP (Thin Quad FlatPack), Small Outline (SOIC), aSSOP (Shrink Small Outline Package), a TSOP (Thin Small Outline), a SIP(System In Package), a MCP (multi-chip Package), a WFP (Wafer-levelFabricated Package), and a WSP (Wafer-level process Stack Package), butthe scope of the present disclosure is not limited thereto.

As described above, the package 100 may include a memory controller 130and a plurality of memory chips 141 to 148. In some example embodiments,the memory controller 130 may include hardware such as logic circuits; ahardware/software combination, such as a processor executing software;or a combination thereof. For example, a processor may include, but isnot limited to, a central processing unit (CPU), an arithmetic logicunit (ALU), a digital signal processor, a microcomputer, a fieldprogrammable gate array (FPGA), a System-on-Chip (SoC), a programmablelogic unit, a microprocessor, application-specific integrated circuit(ASIC), etc.

In the present example embodiment, the external terminal 110 may beimplemented as a plurality of package balls, but the scope of thepresent disclosure is not limited thereto.

In the present example embodiment, the printed circuit board 120 mayinclude a plurality of conductive layers and a through electrode(through-silicon vias: TSV) separated by an insulating layer therein.The conductive layer and the through electrode of the printed circuitboard 120 may be electrically connected to the external terminal 110 ofthe multi-chip package 1.

The memory controller 130 may be electrically connected to the externalterminal 110 of the multi-chip package 1 via the bonding wire A1. Thebonding wire A1 may be connected between a pad of the through electrodeof the printed circuit board 120 connected to the external terminal 110and a pad of the memory controller 130. In some example embodiments ofthe present disclosure, the bonding wire A1 may be connected between thepad, to which the conductive layer of the printed circuit board 120connected to the external terminal 110 is connected, and the pad of thememory controller 130.

Each of the plurality of memory chips 141 to 148 may include anonvolatile memory device. The nonvolatile memory device may includenonvolatile memory element such as a NAND type flash memory, a NOR typeflash memory, a phase change memory (PRAM), a resistance memory (ReRAM),and a magnetoresistive memory (MRAM). For convenience of explanation,the nonvolatile memory device is described on the basis of NAND typeflash memory in this specification.

The nonvolatile memory device includes a memory cell array including aplurality of memory cells constituted by a plurality of rowscorresponding to word lines and a plurality of columns corresponding tobit lines. Each memory cell may store 1-bit data or M-bit data (here, Mis an integer of 2 or more). Each memory cell may be implemented as amemory cell having a charge storage layer such as a floating gate or acharge trap layer, or a memory cell having a variable resistance elementor the like.

The memory cell array may be implemented in a single-layer arraystructure or a two-dimensional array structure, or may be implemented ina multi-layer array structure or a three-dimensional array structure. Insome example embodiments of the present disclosure, thethree-dimensional array structure may include NAND strings disposedvertically such that at least one memory cell is located above anothermemory cell.

The nonvolatile memory devices of the plurality of memory chips 141 to148 may constitute a single channel controlled by the memory controller130. In some example embodiments of the present disclosure, nonvolatilememory devices operating independently of each other may constitute asingle channel. For example, the plurality of memory chips 141 to 144may constitute a first channel, and the plurality of memory chips 145 to148 may constitute a second channel.

The plurality of memory chips 141 to 144 may be electrically connectedto the memory controller 130 via the bonding wires B1 to B4. The bondingwires B1 to B4 may transmit commands, addresses and data, which areprovided from the memory controller 130, to the plurality of memorychips 141 to 144. The bonding wires B1 to B4 may constitute signal linesof the channel.

For example, the bonding wire B1 may be connected between the memorycontroller 130 and the memory chip 141, the bonding wire B2 may beconnected between the memory chip 141 and the memory chip 142, thebonding wire B3 may be connected between the memory chip 142 and thememory chip 143, and the bonding wire B4 may be connected between thememory chip 143 and the memory chip 144.

The plurality of memory chips 145 to 148 may be electrically connectedto the memory controller 130 via the bonding wires C1 to C4. The bondingwires C1 to C4 may transmit commands, addresses and data, which areprovided from the memory controller 130, to the plurality of memorychips 145 to 148. The bonding wires C1 to C4 may constitute the signallines of the channel.

For example, the bonding wire C1 may be connected between the memorycontroller 130 and the memory chip 145, the bonding wire C2 may beconnected between the memory chip 145 and the memory chip 146, thebonding wire C3 may be connected between the memory chip 146 and thememory chip 147, and the bonding wire C4 may be connected between thememory chip 147 and the memory chip 148.

The bonding wires (B1 to B4 and C1 to C4) between the memory controller130 and the plurality of memory chips 141 to 148 are not directlyconnected to the external terminal 110 of the multi-chip package 1.However, defects may occur in the manufacturing process of themulti-chip package 1.

As an example of the defects, two or more bonding wires B4 and C1 may beshort-circuited. The bonding wire used for the multi-chip package 1 hasa fine thickness and is made of a metal such as gold, but it is notseparately provided with an insulating coating. Therefore, after theprinted circuit board 120, the memory controller 130, the plurality ofmemory chips 141 to 148, and the like are all mounted on the multi-chippackage 1, and the bonding wires (B1 to B4 and C1 to C4) are connected,in the course of filling the material for filling the package 100A,short-circuit may occur between the bonding wires (B1 to B4 and C1 toC4).

As another example of the defects, while some of the bonding wires (B1to B4 and C1 to C4) connected to the memory controller 130 or theplurality of memory chips 141 to 148 in the manufacturing process aredetached from the memory controller 130 or the plurality of memory chips141 to 148, an open channel between the memory controller 130 and thememory chips 141 to 148 may occur.

However, since the bonding wires (B1 to B4 and C1 to C4) are notdirectly connected to the external terminal 110 of the multi-chippackage 1, it is difficult to detect defects occurring in the multi-chippackage 1 only with the signal applied to the external terminal 110.Hereinafter, various example embodiments of the present disclosure foraccurately detecting defects such as short-circuit and open which mayoccur inside the multi-chip package 1 will be described.

FIG. 2 is a block diagram illustrating an operation in a normal mode ofthe multi-chip package of FIG. 1. Further, FIG. 3 is a diagramillustrating an example embodiment of an interface circuit 135 of themulti-chip package of FIG. 2.

First, referring to FIG. 2, the multi-chip package 1 of FIG. 1 mayoperate in the normal mode. The normal mode is an operation mode of themulti-chip package 1 distinguished from a test mode to be describedlater, and the memory controller 130 of the multi-chip package 1 of thepresent disclosure may read data stored in the memory chips 144 and 145or may record the data in the memory chips 144 and 145 in the normalmode.

First, the memory chip 145 includes an output driver that outputs datato a bonding pad 1452. An output driver of the memory chip 145 mayinclude drive transistors TR1 and TR2 connected in series with eachother and gated by a signal S1. Here, the drive transistor TR1 mayprovide a power supply voltage VDD to the bonding pad 1452, and thedrive transistor TR2 may provide a ground voltage to the bonding pad1452.

The bonding pad 1452 is electrically connected to the bonding pad 133 ofthe memory controller 130 via the bonding wire C1. As a result, thememory controller 130 may receive the data D1 that is read from thememory chip 145, through the bonding pad 133.

On the other hand, the memory chip 144 includes an output driver thatoutputs data to the bonding pad 1442. The output driver of the memorychip 144 may include drive transistors TR3 and TR4 connected in seriesto each other and gated by a signal S2. Here, the drive transistor TR3may provide the power supply voltage VDD to the bonding pad 1442, andthe drive transistor TR4 may provide the ground voltage to the bondingpad 1442.

The bonding pad 1442 is electrically connected to the bonding pad 132 ofthe memory controller 130 via the bonding wires B4 to B1. As a result,the memory controller 130 may receive the data D2, which is read fromthe memory chip 144, through the bonding pad 132.

In this example embodiment, the memory controller 130 includes theaforementioned bonding pads 132 and 133, and the bonding pad 139electrically connected to the external terminal 110 of FIG. 1 via thebonding wire A1. In addition, the memory controller 130 includes aninterface circuit 135 arranged between the bonding pads 132 and 133 andthe bonding pad 139.

The interface circuit 135 may receive input of data D1 read from thememory chip 145 through the bonding pad 133, and data D2 read from thememory chip 144 via the bonding pad D2. Further, the interface circuit135 may output one of the data D1 and D2 to the external terminal 110via the bonding pad 139 in the normal mode.

Specifically, in the present example embodiment, the interface circuit135 includes a path selection logic 137 and a test logic 138.

The path selection logic 137 may operate in the normal mode or the testmode. For example, the path selection logic 137 may be provided withsetting values for setting the operation mode from the outside, asindicated by “MODE=NORMAL” in FIG. 2 and “MODE=TEST” in FIG. 4. In thenormal mode, the path selection logic 137 may control the test logic 138to output only one output of the output driver of the memory chip 145and the output driver of the memory chip 144.

That is, the path selection logic 137 may control the test logic 138 tooutput only the data D1 as data D3, among data D1 having the first logicvalue H provided from the output driver of the memory chip 145 and dataD2 having a second logic value L provided from the output driver of thememory chip 144. To this end, the path selection logic 137 may provide aselection signal SEL to the test logic 138.

Next, referring to FIG. 3, the path selection logic 137 provides a firstselection signal SEL1 and a second selection signal SEL2 for controllingthe test logic 138 to the test logic 138.

The test logic 138 bypasses the data selected by the path selectionlogic 137 in the normal mode. Nevertheless, the test logic 138 may beimplemented to include a plurality of logic gates G1, G2 and G3 thatexert their functions in a test mode to be described later.

Specifically, the test logic 138 may include a first logic gate G1 whichreceives the data D1 and the first selection signal SEL1 and executesthe first logic operation to output an intermediate data D4, a secondlogic gate G2 which receives the data D2 and the second selection signalSEL2 and executes a second logic operation to output an intermediatedata D5, and a third logic gate G3 which receives the intermediate dataD4 and the intermediate data D5 and executes a third logic operation tooutput the data D3.

When the logic value of the first selection signal SEL1 is the firstlogic value H and the logic value of the second selection signal SEL2 isthe second logic value L, the test logic 138 operates in the normal modeand outputs the data D1 as the data D3. FIG. 3 illustrates such a case.

Alternatively, when the logic value of the first selection signal SEL1is the second logic value L and the logic value of the second selectionsignal SEL2 is the first logic value H, the test logic 138 operates inthe normal mode and outputs the data D2 as the data D3.

Alternatively, when both the logic values of the first selection signalSEL1 and the second selection signal SEL2 are the second logic value L,the test logic 138 operates in the test mode.

In particular, when the test logic 138 operates in the test mode, thedata D1 and the data D2 are test data and the data D3 are the detecteddata, and this will be described below with reference to FIG. 8.

Further, in the present example embodiment, the first logic operationand the second logic operation may include a NOR logic operation, andthe third logic operation may include a NAND logic operation. However,the specific implementation of the test logic 138 is not limited to thisexample embodiment, and may be modified as much as necessary.

In the present example embodiment, since the path selection logic 137operates in the normal mode, the test logic 138 bypasses the dataselected by the path selection logic 137, and finally the memorycontroller 130 may output the values, which are read from the memorychip 144 or the memory chip 145, to the external terminal 110.

FIG. 4 is a block diagram illustrating an operation example in the testmode of the multi-chip package of FIG. 1. Further, FIG. 5 is a diagramillustrating an operation example of the interface circuit 135 of themulti-chip package of FIG. 4.

First, referring to FIG. 4, in this example, a short circuit occursbetween the bonding wire C1 and the bonding wires B4 to B1. As a result,an electrical path is formed between the bonding pad 1452 and thebonding pad 1442.

The multi-chip package 1 may operate in the test mode for detectingdefects to detect such defects. To this end, the multi-chip package 1may further include a strength control module 150. The strength controlmodule 150 may be implemented inside the memory controller 130 or may beimplemented at an arbitrary position outside the memory controller 130.In addition, the strength control module 150 may be mounted on at leastone of the plurality of memory chips 141 to 148.

The strength control module 150 controls drive strength of the outputdriver of the memory chip 145 and the output driver of the memory chip144, respectively. Here, the drive strength is related to the amount ofload that may be driven by the drive transistor, and there is a relationin which, the amount of drivable load is large when the drive strengthis high, and the amount of drivable load is small when the drivestrength is low.

That is, the strength control module 150 sets the drive strength of theoutput driver of the memory chip 144 and the drive strength of theoutput driver of the memory chip 145 to be different from each other,such that the drive strength of the output driver of the memory chip 145and the drive strength of the output driver of the memory chip 144 aremismatched.

For example, the strength control module 150 may set the drive strengthof the drive transistor TR1 of the output driver of the memory chip 145to 1, and may set the drive strength of the drive transistor TR4 of theoutput driver of the memory chip 144 to 10. Further, the multi-chippackage 1 appropriately sets the signals S1 and S2 and turns on thedrive transistor TR1 of the memory chip 145 and the drive transistor TR4of the memory chip 144.

In a case where no short circuit occurs between the bonding wire C1 andthe bonding wires B4 to B1, when the drive transistor TR1 of the memorychip 145 and the drive transistor TR4 of the memory chip 144 are turnedon, the bonding pad 1452 and the bonding pad 133 have a first logicvalue H, and the bonding pad 1442 and the bonding pad 132L have a secondlogic vale L.

As the short circuit occurs between the bonding wire C1 and the bondingwires B4 to B1, and according to voltage dividing by setting the drivestrength of the drive transistor TR4 to be greater than the drivestrength of the drive transistor TR1, the bonding pads 1452, 1442, 133and 132 all have the second logic value L.

That is, in the case of the first test data D1 provided to the memorycontroller 130 via the bonding pad 1452 and the bonding pad 133, a dataflip in which the value changes from the first logic value H to thesecond logic value L by the strength control module 150 occurs. As aresult, the value of the data output via the bonding pad 139 is alsochanged from the first logic value H to the second logic value L.

The strength control module 150 sets the drive strength of the outputdriver of the memory chip 144 and the drive strength of the outputdriver of the memory chip 145 to be different from each other such thatdata flip of the first test data D1 or the second test data D2 occurs inthis way.

Then, the interface circuit 135 receives each of the first test data D1and the second test data D2 from the output driver of the memory chip144 and the output driver of the memory chip 145 in which the drivestrength is set by the strength control module 150, and outputsdetection data D3 for detecting whether the bonding wire C1 and thebonding wires B4 to B1 are short-circuited from the first test data D1and the second test data D2.

Next, referring to FIG. 5, the path selection logic 137 may provide thetest logic 138 with the first selection signal SEL1 and the secondselection signal SEL2 for controlling the test logic 138 to generatedetection data D3 from the first test data D1 and the second test dataD2. Here, the first selection signal SEL1 and the second selectionsignal SEL2 may have a second logic value L.

The first logic gate G1 of the test logic 138 receives the first testdata D1 and the first selection signal SEL1 and executes a first logicoperation to generate intermediate data D4, and the second logic gate G2receives the second test data D2 and the second selection signal SEL2and executes the second logic operation to output the intermediate dataD5. Further, the third logic gate G3 receives the intermediate data D4and the intermediate data D5 and executes a third logic operation tooutput the detection data D3.

Here, the detection data D3 includes a first logic value H when no shortcircuit occurs between the first bonding wire C1 and the bonding wiresB4 to B1, and the detection data D3 includes the second logic value Ldifferent from the first logic value H and when a short circuit occursbetween the bonding wire C1 and the bonding wires B4 to B1.

That is, in the present example embodiment, the first test data D1 isflipped from the first logic value H to the second logic value L, thevalue of the intermediate data D4 is also flipped from the second logicvalue L to the first logic value H, and thus, the detection data D3 isalso flipped from the first logic value H to the second logic value L.

That is, the strength control module 150 sets the drive strength of thedrive transistor TR4 of the output driver of the memory chip 144 to begreater than the drive strength of the drive transistor TR1 of theoutput driver of the memory chip 145, thereby inducing the data flip.

Since the detection data D3 determined in this manner is output via theexternal terminal 110, it is possible to accurately detect defects suchas a short-circuit that may occur in the multi-chip package 1, byanalyzing the detection data D3.

FIG. 6 is a block diagram illustrating an operation example in the testmode of the multi-chip package of FIG. 1. FIG. 7 is a diagramillustrating an operation example of the interface circuit 135 of themulti-chip package of FIG. 6.

First, referring to FIG. 6, in the same manner as in the precedingexample, a short circuit occurred between the bonding wire C1 and thebonding wires B4 to B1. As a result, an electrical path is formedbetween the bonding pad 1452 and the bonding pad 1442.

In the present example embodiment, the strength control module 150 mayset the drive strength of the drive transistor TR3 of the output driverof the memory chip 144 to 1, and may set the drive strength of the drivetransistor TR2 of the output driver of the memory chip 145 to 10.Further, the multi-chip package 1 appropriately sets the signals S1 andS2 to turn on the drive transistor TR2 of the memory chip 145 and thedrive transistor TR3 of the memory chip 144.

In a case where the short circuit does not occur between the bondingwire C1 and the bonding wires B4 to B1, when the drive transistor TR2 ofthe memory chip 145 and the drive transistor TR3 of the memory chip 144are turned on, the bonding pad 1452 and the bonding pad 133 have thesecond logic value L, and the bonding pad 1442 and the bonding pad 132have the first logic value H.

As a short circuit occurs between the bonding wire C1 and the bondingwires B4 to B1, and according to the voltage dividing by setting thedrive strength of the drive transistor TR2 to be greater than the drivestrength of the drive transistor TR3, the bonding pads 1452, 1442, 133and 132 all have the second logic value L.

That is, in the case of the second test data D2 provided to the memorycontroller 130 via the bonding pad 1442 and the bonding pad 132, a dataflip in which the value is changed from the first logic value H to thesecond logic value L by the strength control module 150 occurs. As aresult, the value of the data output through the bonding pad 139 is alsochanged from the first logic value H to the second logic value L.

Next, referring to FIG. 7, here, the detection data D3 includes thefirst logic value H when no short circuit between the first bonding wireC1 and the bonding wires B4 to B1 occurs, and the detection data D3includes the second logic value L different from the first logic value Hwhen a short circuit between the first bonding wire C1 and the bondingwires B4 to B1 occurs.

That is, in the present example embodiment, the second test data D2 isflipped from the first logic value H to the second logic value L, thevalue of the intermediate data D5 is also flipped from the second logicvalue L to the first logic value H, and thus, the detection data D3 isalso flipped from the first logic value H to the second logic value L.

That is, the strength control module 150 sets the drive strength of thedrive transistor TR3 of the output driver of the memory chip 144 to besmaller than the drive strength of the drive transistor TR2 of theoutput driver of the memory chip 145, thereby inducing the data flip.

Since the detection data D3 determined in this manner is output throughthe external terminal 110, it is possible to accurately detect defectssuch as a short circuit that may occur inside the multi-chip package 1,by analyzing the detection data D3.

FIG. 8 is a table illustrating the operation of the multi-chip packageof FIG. 1.

Referring to FIG. 8, case ‘1’ corresponds to the example embodimentdescribed with reference to FIGS. 4 and 5, and case ‘2’ corresponds tothe example embodiment described with reference to FIGS. 6 and 7.

In case “1”, when the drive strength of the drive transistor TR1 of thememory chip 145 is set to be weak in a channel #0 between the memorychip 145 and the memory controller 130, and the drive strength of thedrive transistor TR4 of the memory chip 144 is set to be strong in achannel #1 between the memory chip 144 and the memory controller 130, ifthere is a defect of short circuit, since the test data D1 is flippedfrom the first logic value H, the detection data D3 has the second logicvalue L.

In case “2”, when the drive strength of the drive transistor TR2 of thememory chip 145 is set to be strong in the channel #0 between the memorychip 145 and the memory controller 130, and the drive strength of thedrive transistor TR3 of the memory chip 144 is set to be weak in thechannel #1 between the memory chip 144 and the memory controller 130, ifthere is a defect of short circuit, since the test data D2 is flippedfrom the first logic value H, the detection data D3 has the second logicvalue L.

Since the detection data D3 determined in this manner is output throughthe external terminal 110, it is possible to accurately detect defectssuch as a short circuit that may occur in the multi-chip package 1, byanalyzing the detection data D3.

FIG. 9 is a cross-sectional view illustrating a multi-chip packageaccording to an example embodiment of the present disclosure.

Referring to FIG. 9, the multi-chip package 1 includes a package 100 andan external terminal 110. Further, the package 100 includes a memorycontroller 130 and a plurality of memory chips 141 to 148 mounted on theprinted circuit board 120.

The nonvolatile memory devices of the plurality of memory chips 141 to148 may constitute a single channel controlled by the memory controller130. In some example embodiments of the present disclosure, thenonvolatile memory devices operating independently of each other mayconstitute a single channel. For example, the plurality of memory chips141 to 144 constitute a first channel, and the plurality of memory chips145 to 148 may constitute a second channel.

The plurality of memory chips 141 to 144 may be electrically connectedto the memory controller 130 through the bonding wires B1 to B4. Thebonding wires B1 to B4 may transmit commands, addresses, and data, whichare provided from the memory controller 130, to the plurality of memorychips 141 to 144. The bonding wires B1 to B4 may constitute the signallines of the channel.

For example, the bonding wire B1 may be connected between the memorycontroller 130 and the memory chip 141, the bonding wire B2 may beconnected between the memory chip 141 and the memory chip 142, thebonding wire B3 may be connected between the memory chip 142 and thememory chip 143, and the bonding wire B4 may be connected between thememory chip 143 and the memory chip 144.

The plurality of memory chips 145 to 148 may be electrically connectedto the memory controller 130 via the bonding wires C1 to C4. The bondingwires C1 to C4 may transmit commands, addresses, and data, which areprovided from the memory controller 130, to the plurality of memorychips 145 to 148. The bonding wires C1 to C4 may constitute the signallines of the channel.

For example, the bonding wire C1 may be connected between the memorycontroller 130 and the memory chip 145, the bonding wire C2 may beconnected between the memory chip 145 and the memory chip 146, thebonding wire C3 may be connected between the memory chip 146 and thememory chip 147, and the bonding wire C4 may be connected between thememory chip 147 and the memory chip 148.

In this example embodiment, the memory chip 146 of the multi-chippackage 1 is not connected to the bonding wire. In other words, this isa case where the channel formed between the memory controller 130 andthe memory chip 146 is opened.

FIG. 10 is a block diagram illustrating the multi-chip package of FIG.9. Further, FIG. 11 is a block diagram illustrating an operation examplein the test mode of the multi-chip package of FIG. 9.

Referring to FIGS. 10 and 11 together, in the present exampleembodiment, the interface circuit 135 supports an ODT (On DieTermination). The ODT is a technique for making a termination resistorfor impedance matching of the transmission line be located inside thesemiconductor chip. Since this technique is a well-known technique,detailed description thereof will not be provided in this specification.

In this example embodiment, the multi-chip package 1 may further includea strength control module 150. The strength control module 150 may beimplemented inside the memory controller 130 or may be implemented at anarbitrary position outside the memory controller 130. In addition, thestrength control module 150 may be mounted on at least one of theplurality of memory chips 141 to 148.

The strength control module 150 controls the output driver of the memorychip 146 and the drive strength of the interface circuit 135,respectively. Here, the drive strength is related to an amount of loadthat may be driven by the drive transistor, and there is a relation inwhich the amount of drivable load is large when the drive strength ishigh, and the amount of drivable load is small when the drive strengthis low.

Specifically, the strength control module 150 sets the drive strength ofthe output driver of the memory chip 146 and the drive strength of theinterface circuit 135 so that the data flip of the data output from theoutput driver of the memory chip 146 occurs.

For example, the output driver of the memory chip 146 includes a drivetransistor TR5 which provides a power supply voltage VDD, and a drivetransistor TR6 which provides a ground voltage. Further, the interfacecircuit 135 includes a drive transistor TR7 which provides a powersupply voltage VDD, and a drive transistor TR8 which provides a groundvoltage.

In this case, the strength control module 150 sets the drive strength ofthe drive transistor TR8 to be smaller than the drive strength of thedrive transistor TR7. Further, the drive strength of the drivetransistor TR6 is set to be greater than the drive strength of the drivetransistor TR7.

In the present example embodiment, since the strength control module 150sets the drive strength of the drive transistor TR7 to 3 and sets thedrive strength of the drive transistor TR8 to 1, the drive strength ofthe drive transistor TR8 is smaller than the drive strength of the drivetransistor TR7.

Further, in the present example embodiment, since the strength controlmodule 150 sets the drive strength of the drive transistor TR6 to 10,the drive strength of the drive transistor TR6 is greater than the drivestrength of the drive transistor TR7.

Further, the strength control module 150 sets the drive strength of thedrive transistor TR5 to 5.

When an open channel between the memory chip 146 and the interfacecircuit 135 does not occur, the value output from the memory chip 146 istransmitted to the bonding pad 134 and is output through the bonding pad139. In this case, since the drive strength of the drive transistor TR5is 5 and the drive strength of the drive transistor TR6 is 10, thebonding pad 134 needs to have the second logic value L according to thevoltage dividing.

However, as illustrated in FIG. 11, when an open channel between thememory chip 146 and the interface circuit 135 occurs, since the drivestrength of the drive transistor TR7 is 3 and the drive strength of thedrive transistor TR8 is 1, the bonding pad 134 is flipped from thesecond logic value L to the first logic value H in accordance with thevoltage dividing.

That is, the interface circuit 135 may output the detection data D6 fordetecting whether an open channel between the memory chip 146 and theinterface circuit 135 occurs, using the output driver of the memory chip146 and the interface circuit 135 in which the drive strength is set bythe strength control module 150.

Here, the detection data D6 includes the second logic value L when noopen o channel between the memory chip 146 and the interface circuit 135occurs, and the detection data D6 may include the first logic value Hdifferent from the second logic value L when the open channel betweenthe memory chip 146 and the interface circuit 135 occurs.

By analyzing the detection data D6 thus determined, it is possible toaccurately detect the defect such as the opening which may occur insidethe multi-chip package 1.

FIG. 12 is a block diagram illustrating a multi-chip package accordingto an example embodiment of the present disclosure. FIG. 13 is a blockdiagram illustrating an operation example in the test mode of themulti-chip package of FIG. 12.

Referring to FIG. 12, the interface circuit 135 includes a drivetransistor TR9 which provides a power supply voltage VDD to the memorychip 146, and a drive transistor TR10 which provides a ground voltage tothe memory chip 146. In the present example embodiment, it is possibleto detect whether the channel between the memory chip 146 and the memorycontroller 130 is opened, using the drive transistor TR9 and the drivetransistor TR10.

In this example embodiment, the memory chip 146 further includes abonding pad 1462 electrically connected to the bonding wires C1 to C2,and a pull-up circuit 1464 electrically connected to the bonding pad1462 to pull up the bonding pad 1462. Here, the configuration of thepull-up circuit 1464 is not limited to a specific circuit, and may beimplemented as an arbitrary circuit that pulls up a voltage level of thebonding pad 1462. Further, the pull-up circuit 1464 may be implementedinside the memory chip 146 or may be implemented outside the memory chip146.

In the test mode, the pull-up circuit 1464 of the memory chip 146, andthe drive transistor TR10 of the interface circuit may be turned on.

As illustrated in FIG. 12, when the open channel between the memory chip146 and the memory controller 130 does not occur, the amount of currentflowing through the drive transistor TR10 increases. As illustrated inFIG. 13, when the open channel between the memory chip 146 and thememory controller 130 occurs, the amount of current flowing through thedrive transistor TR10 does not increase.

Therefore, in the present example embodiment, it is possible to detectwhether the channel between the memory chip 146 and the memorycontroller 130 is opened by monitoring the change in the amount ofcurrent flowing through the drive transistor TR10.

FIG. 14 is a block diagram illustrating a multi-chip package accordingto an example embodiment of the present disclosure. FIG. 15 is a blockdiagram illustrating an operation example in the test mode of themulti-chip package of FIG. 14.

Referring to FIG. 14, the interface circuit 135 includes a drivetransistor TR9 which provides a power supply voltage VDD to the memorychip 146, and a drive transistor TR10 which provides a ground voltage tothe memory chip 146. Also in the present example embodiment, it ispossible to detect whether the channel between the memory chip 146 andthe memory controller 130 is opened, using the drive transistor TR9 andthe drive transistor TR10.

In this example embodiment, the memory chip 146 further includes abonding pad 1462 electrically connected to the bonding wires C1 to C2,and a full-down circuit 1466 electrically connected to the bonding pad1462 to pull down the bonding pad 1462. Here, the configuration of thepull-down circuit 1466 is not limited to a specific circuit, and may beimplemented as an arbitrary circuit that pulls down the voltage level ofthe bonding pad 1462. Further, the pull-down circuit 1466 may beimplemented inside the memory chip 146 or may be implemented outside thememory chip 146.

In the test mode, the pull-down circuit 1466 of the memory chip 146 andthe drive transistor TR9 of the interface circuit may be turned on.

As illustrated in FIG. 14, when the open channel between the memory chip146 and the memory controller 130 does not occur, the amount of currentflowing through the drive transistor TR9 increases. As illustrated inFIG. 15, when the open channel between the memory chip 146 and thememory controller 130 occurs, the amount of current flowing through thedrive transistor TR9 does not increase.

Therefore, in the present example embodiment, it is possible to detectwhether the channel between the memory chip 146 and the memorycontroller 130 is opened, by monitoring the change in the amount ofcurrent flowing through the drive transistor TR9.

According to various example embodiments of the present disclosuredescribed thus far, it is possible to accurately detect defects such asshort-circuit and opening which may occur inside the multi-chip package.

In concluding the detailed description, those skilled in the art willappreciate that many variations and modifications may be made to theexample embodiments without substantially departing from the principlesof the present disclosure. Therefore, the disclosed example embodimentsof the disclosure are used in a generic and descriptive sense only andnot for purposes of limitation.

What is claimed is:
 1. A multi-chip package comprising: a first memorychip and a second memory chip on a printed circuit board; a memorycontroller electrically connected to the first memory chip and thesecond memory chip via a first bonding wire and a second bonding wire;and a strength control module configured to control a drive strength ofeach of a first output driver of the first memory chip and a secondoutput driver of the second memory chip, wherein the memory controllerincludes an interface circuit configured to receive each of first testdata and second test data from the first output driver and the secondoutput driver in which the drive strength is set by the strength controlmodule, and output detection data for detecting whether the firstbonding wire and the second bonding wire are short-circuited based onthe first and second test data.
 2. The multi-chip package of claim 1,wherein the strength control module is configured to set the drivestrength of the first output driver and the drive strength of the secondoutput driver to be different from each.
 3. The multi-chip package ofclaim 2, wherein the strength control module is configured to set thedrive strength of the first output driver and the drive strength of thesecond output driver to be different from each other such that a dataflip of the first test data or the second test data occurs.
 4. Themulti-chip package of claim 3, wherein the strength control module isconfigured to set the drive strength of a drive transistor of the secondoutput driver to be greater than the drive strength of a drivetransistor of the first output driver.
 5. The multi-chip package ofclaim 3, wherein the strength control module is configured to set thedrive strength of a drive transistor of the second output driver to besmaller than the drive strength of a drive transistor of the firstoutput driver.
 6. The multi-chip package of claim 1, wherein theinterface circuit includes a path selection logic and a test logic, andbased on operating in a test mode, the path selection logic isconfigured to control the test logic to generate the detection data fromthe first test data and the second test data.
 7. The multi-chip packageof claim 6, wherein based on operating in a normal mode, the pathselection logic is configured to control the test logic to select onlyone output of the first output driver and the second output driver. 8.The multi-chip package of claim 6, wherein the path selection logic isconfigured to provide the test logic with a first selection signal and asecond selection signal for controlling the test logic, and the testlogic includes a first logic gate configured to receive the first testdata and the first selection signal and perform a first logic operationto output first intermediate data, a second logic gate configured toreceive the second test data and the second selection signal and performa second logic operation to output second intermediate data, and a thirdlogic gate configured to receive the first intermediate data and thesecond intermediate data and perform a third logic operation to outputthe detection data.
 9. The multi-chip package of claim 8, wherein thetest logic outputs the detection data to an external terminal through abonding pad.
 10. The multi-chip package of claim 8, wherein thedetection data includes a first logic value based on no short circuitbetween the first bonding wire and the bonding wire occurring, and asecond logic value different from the first logic value based on a shortcircuit between the first bonding wire and the bonding wire occurring.11. A multi-chip package comprising: a memory chip on a printed circuitboard; a memory controller electrically connected to the memory chipthrough a bonding wire and including an interface circuit for drivingthe memory chip; and a strength control module configured torespectively control drive strengths of output drivers of the memorychip and the interface circuit, wherein the interface circuit isconfigured to output, using the output drivers of the memory chip andthe interface circuit, detection data for detecting whether an openchannel between the memory chip and the interface circuit exists. 12.The multi-chip package of claim 11, wherein the strength control moduleis configured to respectively set the drive strengths of the outputdrivers of the memory chip and the drive strength of the interfacecircuit so that a data flip of the data output from the interfacecircuit occurs.
 13. The multi-chip package of claim 12, wherein theinterface circuit includes a first drive transistor configured toprovide a power supply voltage, and a second drive transistor configuredto provide a ground voltage, and the strength control module isconfigured to set the drive strength of the second drive transistor tobe smaller than the drive strength of the first drive transistor. 14.The multi-chip package of claim 13, wherein the strength control moduleis configured to set the drive strength of a third drive transistor ofthe memory chip to be greater than the drive strength of the first drivetransistor.
 15. The multi-chip package of claim 11, wherein thedetection data includes a first logic value based on no open channelbetween the memory chip and the interface circuit existing, and includesa second logic value different from the first logic value based on anopen channel between the memory chip and the interface circuit existing.16. A multi-chip package comprising: a memory chip on a printed circuitboard; and a memory controller electrically connected to the memory chipthrough a bonding wire and including an interface circuit configured todrive the memory chip, wherein the interface circuit includes a firstdrive transistor configured to provide a power supply voltage to thememory chip, and a second drive transistor configured to provide aground voltage to the memory chip; and the interface circuit configuredto detect, using the first drive transistor and the second drivetransistor, whether a channel between the memory chip and the memorycontroller is open.
 17. The multi-chip package of claim 16, wherein thememory chip comprises: a bonding pad electrically connected to thebonding wire, and a pull-up circuit electrically connected to thebonding pad to pull up the bonding pad.
 18. The multi-chip package ofclaim 17, wherein, based on no open channel between the memory chip andthe memory controller existing, an amount of current flowing through thesecond drive transistor increases, and based on an open channel betweenthe memory chip and the memory controller existing, the amount ofcurrent flowing through the second drive transistor does not increase.19. The multi-chip package of claim 16, wherein the memory chipcomprises: a bonding pad electrically connected to the bonding wire, anda pull-down circuit electrically connected to the bonding pad to pulldown the bonding pad.
 20. The multi-chip package of claim 19, wherein,based on no open channel between the memory chip and the memorycontroller existing, an amount of current flowing through the firstdrive transistor increases, and based on an open of the channel betweenthe memory chip and the memory controller existing, the amount ofcurrent flowing through the first drive transistor does not increase.